XTC+: descripción y análisis de un mecanismo de control de topología para los MANET

The Objective of topology control mechanisms (TCM) is to modify the natural network topology toward a determined objective. In MANETs the objective is to minimize power consumption and/or interference. In general topology control is achieved through deliberate changes in transmission power (and possibly other parameters such as antenna direction and channel selection) that directly affect the local connectivity of a node, and consequently affect the whole topology of the network. By focusing on the stage in which information is collected in an existing topology control algorithm called XTC, this paper shows the possibility of extending the network performance optimization present in this algorithm. It is then an addition to an already existing optimization concept.El objetivo de los mecanismos de control de topología (TCM) es modificar la topología de la red natural hacia un objetivo determinado. En los MANET el objetivo es minimizar el consumo de energía y/o de interferencia. En la topología general el control se alcanza mediante cambios deliberados en la potencia de transmisión (y posiblemente en otros parámetros como la dirección de la antena y la selección de canal) que afectan directamente la conectividad local de un nodo y en consecuencia, afectan toda la topología de la red. Este artículo muestra la posibilidad de prolongar la optimización del desempeño de la red presente en este algoritmo, mediante el enfoque en la etapa en que la información es recopilada en un algoritmo de control de topología existente llamado XTC. Es entonces, un complemento a un concepto de optimización ya existente

Exact algorithms to minimize interference in wireless sensor networks

AbstractFinding a low-interference connected topology is a fundamental problem in wireless sensor networks (WSNs). The problem of reducing interference through adjusting the nodes’ transmission radii in a connected network is one of the most well-known open algorithmic problems in wireless sensor network optimization. In this paper, we study minimization of the average interference and the maximum interference for the highway model, where all the nodes are arbitrarily distributed on a line. First, we prove that there is always an optimal topology with minimum interference that is planar. Then, two exact algorithms are proposed. The first one is an exact algorithm to minimize the average interference in polynomial time, O(n3Δ), where n is the number of nodes and Δ is the maximum node degree. The second one is an exact algorithm to minimize the maximum interference in sub-exponential time, O(n3ΔO(k)), where k=O(Δ) is the minimum maximum interference. All the optimal topologies constructed are planar

XTC+: descripción y análisis de un mecanismo de control de topología para los MANET

El objetivo de los mecanismos de control de topología (TCM) es modificar la topología de la red natural hacia un objetivo determinado. En los MANET el objetivo es minimizar el consumo de energía y/o de interferencia. En la topología general el control se alcanza mediante cambios deliberados en la potencia de transmisión (y posiblemente en otros parámetros como la dirección de la antena y la selección de canal) que afectan directamente la conectividad local de un nodo y en consecuencia, afectan toda la topología de la red. Este artículo muestra la posibilidad de prolongar la optimización del desempeño de la red presente en este algoritmo, mediante el enfoque en la etapa en que la información es recopilada en un algoritmo de control de topología existente llamado XTC. Es entonces, un complemento a un concepto de optimización ya existente

Topology preservation and control approach for interference aware non-overlapping channel assignment in wireless mesh networks

The Wireless Mesh Networks (WMN) has attracted significant interests due to their fast and inexpensive deployment and the ability to provide flexible and ubiquitous internet access. A key challenge to deploy the WMN is the interference problem between the links. The interference results in three problems of limited throughput, capacity and fairness of the WMN. The topology preservation strategy is used in this research to improve the throughput and address the problems of link failure and partitioning of the WMN. However, the existing channel assignment algorithms, based on the topology preservation strategy, result in high interference. Thus, there is a need to improve the network throughput by using the topology preservation strategy while the network connectivity is maintained. The problems of fairness and network capacity in the dense networks are due to limited available resources in WMN. Hence, efficient exploitation of the available resources increases the concurrent transmission between the links and improves the network performance. Firstly, the thesis proposes a Topology Preservation for Low Interference Channel Assignment (TLCA) algorithm to mitigate the impact of interference based on the topology preservation strategy. Secondly, it proposes the Max-flow based on Topology Control Channel Assignment (MTCA) algorithm to improve the network capacity by removing useless links from the original topology. Thirdly, the proposed Fairness Distribution of the Non-Overlapping Channels (FNOC) algorithm improves the fairness of the WMN through an equitable distribution of the non-overlapping channels between the wireless links. The F-NOC is based on the Differential Evolution optimization algorithm. The numerical and simulation results indicate that the proposed algorithms perform better compared to Connected Low Interference Channel Assignment algorithm (CLICA) in terms of network capacity (19%), fractional network interference (80%) and network throughput (28.6%). In conclusion, the proposed algorithms achieved higher throughput, better network capacity and lower interference compared to previous algorithms

Reducing interference in ad hoc networks through topology control

Topology control aims to increase the lifetime of an ad hoc network by selecting only a subset of the available links to be used for routing. The tradeoff between keeping the span- ner properties of the graph while sparsifying the graph has been well studied. However, it has often been assumed that a sparse graph implicitly has low interference, but recent research shows that that is not necessarily true. In this pa- per, we discuss different methods to measure interference, and present a new interference model that aims to describe the interference of the entire network, rather than just the worst part of it. We present API, a topology control algorithm that serves two purposes: it minimizes the interference in the network according to our metrics, and it keeps the spanner properties of the original graph. The paper is completed by simulations that compare different topologies with respect to different interference metricsGodkänd; 2005; 20060913 (ysko)</p

Controle de topologia em redes de robôs móveis cooperativos utilizando consenso

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia de Automação e Sistemas, Florianópolis, 2015.Em grupos de robôs móveis cooperativos, os chamados sistemas multi-robôs, a comunicação é um fator de extrema importância para a correta alocação e realização das tarefas. Essa comunicação é determinada diretamente pela disposição geográfica dos robôs uns em relação aos outros, a chamada topologia de comunicação. O controle da topologia de comunicação em um grupo de robôs permite que certas características da rede de comunicação sejam enfatizadas ou anuladas de acordo com a movimentação dos robôs que a compõem. Neste trabalho são apresentadas duas abordagens para controle de topologia em redes de robôs móveis, em função de quais propriedades dessas redes se deseja exaltar: o controle de topologia para a minimização da comunicação, que possibilita a redução do consumo de energia e da interferência causada pelos processos de comunicação; e o controle de topologia para a manutenção da conectividade, que garante condições para a não desconexão da rede, mesmo que esta esteja sob a influência de instabilidades. Através de um controle de conectividade baseado em consenso, a ação dos algoritmos de controle da topologia é aplicada aos robôs de maneira descentralizada, garantindo que as propriedades desejadas ocorram. São realizados simulações e testes com robôs reais, comprovando a eficiência dos algoritmos propostos em garantir as propriedades topológicas a eles associadas.Abstract : In cooperative robot systems, also known as multi-robot systems, the communication is an extremely important factor for the correct allocation and execution of the robot tasks. This communication is directly determined by the geographic position of the robots in relation each other, which is called communication topology. The topology control can be used to change aspects of the communication topology, allowing that some network characteristics are canceled or exalted, according with the robot's movement in the network. This work presents two approaches for topology control in mobile robot networks that ensure certain properties: the topology control for minimization of the communication, reducing the consumption of energy and the interference caused by radio communication; and the topology control for the connectivity maintenance, ensuring conditions for do not disconnection, even under unstable environments. Through of a connectivity control based on consensus, the action of topology control algorithms is applied to the robots in a decentralized way, ensuring the existence of the desired properties. Finally, are made simulations and tests with real robots, proving the efficiency of the proposed algorithms to ensure the functions assigned to them